Linux Learning Notes (25) Shell special symbols, Sort_wc_uniq, tee_tr_split

one, special characters

1.
Any character of ' * '
‘? ' Any one character
' # ' comment characters
' \ ' de-semantic characters
' | ' Pipe character
Most of them have been used before, for the caret ' \ '

Examples of the use of the caret

2. Several pipe-related commands
Cut split,-D delimiter-f Specifies the segment number-C to specify the first few characters


Sort sorted,-N with numeric sort-R reversed-T delimiter-kn1/-kn1,n2
Sort 1.txt//sorting 1.txt
Special characters are least, numbers are second, followed by alphabetical order

Sort-n 1.txt//sorted by number size, special characters and English default size is 0


Wc-l statistics number of rows-m statistic characters-W statistics
-M includes newline characters
-W is separated by a space


Uniq to weight,-c count rows
Uniq need to sort and then go heavy, if not sorted, cannot go to heavy

Tee and > similar, redirect while still on screen display
Output redirection does not display content, tee is displayed on the screen while redirecting
Tee-a Append

TR replacement character, tr ' a ' B ', case replacement TR ' [A-z] ' [A-z] '

Split Cut,-B size (default unit byte),-L line number
find/etc/-type f-name "*.conf"-exec cat {} >>a.txt \;




If you do not specify a name after the cut, the file name is followed by the letter X

Medium ABC is the beginning of the specified file name
Split-l cut by number of lines


Second, special symbols

$ 变量前缀，!$组合，正则里面表示行尾 ；多条命令写到一行，用分号分割 ~ 用户家目录，后面正则表达式表示匹配符 & 放到命令后面，会把命令丢到后台 >                   // 正确重定向  >>               //正确追加重定向   2>             //错误重定向     2>>          //错误追加重定向     &>           //正确错误重定向 [ ] 指定字符中的一个，[0-9],[a-zA-Z],[abc] || 和 && ，用于命令之间

|| Or

Select one, the previous command will not execute the following command if it succeeds
&& the previous command succeeds before the command is executed.

Linux Learning Notes (25) Shell special symbols, Sort_wc_uniq, tee_tr_split